Half as expensive to make yet just as expensive on shelves quite likely.
Even in that scenario, society benefits, because the value of the memory does not depend on the cost of production. The buyer determines the value.
If production costs are halved, society regains half of the resources to be used for other purposes.
In reality, reducing costs makes it more profitable to produce higher volumes at lower prices, but this is a secondary benefit compared to the resources saved.
This is why socialism fails: socialists believe that value is equal to the cost of production, making it impossible to determine what to produce, in what quantities, and at what quality. There are countless uses for the same resource, and the cost remains the same regardless of how the resource is used. For example, using one barrel of oil to build a house or to burn a house has the same "value": it costs the same one barrel of oil. If it takes 1 kg of iron to make a hammer, each hammer has the same "value" whether you make one or a billion. Each hammer has the same cost, but in reality, the first hammer has high real value, because it's scarce, and everybody needs it, while a billion hammers are worthless.
Instead, in capitalism, people does everything possible to make the most valuable products, at the lower cost, to maximize profits. The more profits people makes, the richer and prosperous gts the society. If you make 1 hammer, you make a lot of money, but as you rise production, your profits drop, so you know where to stop, and society can use the remaining resources to maximize the profit making other products.